Motor tuning indicator



June 13, 1939. H. A. REED MOTOR TUNING INDICATOR Fi led June 1, 1937 INSU LATION CONSTANT SPEED MOTOR INVENTOR [17.11.13 eed BY Q ATTO RN EY Patented June 13, 1939 UNITED STATES PATENT OFFECE 4 Claims.

This invention relates generally to an indicating device for use in connection with internal combustion engines of the spark ignition type and in particular is directed to, and it is my principal object to provide, an indicating device for use in connection with motor vehicle engines in order to facilitate the tuning thereof, and to indicate to the mechanic when maximum operating efiiciency is attained.

It is also my object to provide a motor tuning indicator, constructed as heretofore described, which will be compact and light in weight and thus readily portable from place to place.

A further object of the invention is to'produce a simple and inexpensive device and yet one which will be exceedingly effective for the purpose for which it is designed.

These objects I accomplish by means of such structure and relative arrangement of parts as will fully appear by a perusal of the following specification and claims.

In the drawing similar characters of reference indicate corresponding parts in the several views:

Figure 1 is a perspective view of my improved indicator.

Figure 2 is a front elevation of the device connected to a spark plug, and with the front cover removed from the front plate.

Figure 3 is a sectional elevation on line 3-3 30 of Fig. 1.

Referring now more particularly to the characters of reference on the drawing, the indicator comprises a base I formed in unitary connection with an upstanding front plate 2 and a pair of side plates 3. The front plate is normally enclosed by a cover or cap, having a face 4 and sides 4a removably held in place by bolts 5. This cover is constructed, so that its face or wall 4 will be spaced some distance from front plate 2 Al] whereby to form an enclosed chamber 6 therebetween.

A constant speed motor 'I, having an electric supply cable Ta, is mounted on the base I rearwardly of front plate 2, the shaft 8 of the motor projecting through an opening in said plate and terminating within the chamber 6. A disc 9 is fixed on the end of shaft 8 within the chamber, said disc having its periphery formed as one full turn of a spiral. The difference in radius between the ends of the spiral peripheral edge of the disc forms a radial edge l0, said edge being of predetermined length.

A relatively narrow vertically extending window is cut in the face 4 of the cover radial with the disc, the length of the window being substantially equal to the length of radial edge [0 on disc 9, and disposed with its upper end disposed at a point in the plane of the path of movement of the outer end of edge l0. In other words, the window H will register with the path of movement defined by the edge l0 and which path is of a width equal to the length of said edge. The disc thus forms a shutter for said window.

A neon tube I2 is mounted vertically in' an insulated holder I3 rearwardly of the disc 9, such tube being at least the length of the window and is vertically disposed in alinement therewith. A lead wire l4 from the top of the'tube I2 0011-. nects to a projecting terminal I5 while another lead wire it extends from the lower end of the tube to the front plate 2.

In use the device is preferably suspended adjacent the engine of a motor vehicle by means of a hook member I! which may engage over the radiator tie rod or the like. A cable C, having suitable spring clips I8 at each endiand insulated at l9 for ease of handling, is connected between one spark plug S of the engine E to be tuned and the terminal IS in the manner shown in Fig. 2.

The electric supply cable 1a of motor I is then connected to a suitable source of current causing the motor to operate and. rotate disc 9, the motor being of constant speed type as heretofore indicated.

With the disc 9 rotating at constant speed, the vehicle engine is started and accelerated with the hand throttle until the engine speed synchronizes with the speed of the driven disc. Such synchronization is accomplished as follows: The neon tube I2 is actuated and illuminated each time that spark plug S is fired and with the rapid flashing of the neon tube, the peripheral edge of the disc and adjacent disc portion will appear as a shadow or screen in front of the tube and extending upward from the bottom of the window. This shadow will remain immovable when the engine speed and disc speed are synchronized. It should be noted that the engine speed and disc speed need not both be the same R. P. M. in order to obtain such synchronization as such can be accomplished as long as one speed is a multiple of the other.

Having synchronized the engine and disc speeds and at a point with the shadow line preferably disposed intermediate the ends of the window, the mechanic then proceeds to make adjustments of the carburetor, ignition, etc. of the engine with a view to obtaining maximum efficiency. If his adjustments produce the desired result and the engine E speeds up, the shadow rises covering a great portion of the tube. On the other hand, if the engine slows down due to improper adjustment, the shadow will fall. The rising and falling of the shadow is, of course, due to the unsynchronizing of the engine and disc speeds causing an advance or retardation of the flashing and this, taken with the spiral edged disc, produces the desired illusion.

The device is quite sensitive to engine adjustments and may be used as an indicator for any engine adjustment which affects motor speed. In order to make the device easy to read, the interior of chamber 6, the faces of the disc, and the area about the window should be painted black.

From the foregoing description it will be readily seen that I have produced such a device as substantially fulfills the objects'of the invention as set forth herein.

While this specification sets forth in detail the present and preferred construction of the device,

still in practice such deviations from such detail may be resorted to as do not form a departure from the spirit of the invention, as defined by the appended claims.

Having thus described my invention, what I claim as new and useful and desire to secure by Letters Patent is:

l. A motor tuning indicator comprising a shell having a wall, an elongated slot-like'window in said wall, means mounted in the shell and adapted to be actuated from the ignition circuit of an engine when in operation to produce int ermittent flashes of light behind and for the full length of the window, and an opaque disc driven at constant speed mounted in a fixed position in connection with the shell parallel to and adjacent said wall thereof at a point beyond one end of the window, the peripheral edge of the disc being shaped as one full turn ofa' spiral with an abrupt radial edge connecting the outer and inner ends of the spiral edge, the length of said radial edge being substantially equal to the length of the window and positioned to register therewith; the distance from the inner end of the spiral edge to the axis of the disc being substantially the same as the distance from said axis to said one end of the window.

2. A motor tuning indicator comprising a shell having a wall provided with an elongated slot like window, means mounted in the shell and adapted to be actuated from the ignition circuit of an engine when in operation to produce intermittent flashes of light behind and for the full length of the window, an opaque disc parallel to the shell wall, means mounting the disc in connection with the shell adjacent said wall for rotation in a plane parallel thereto with its axis beyond one end of the window and means to rotate the disc at a constant speed; the disc being of such size and formed with an irregular contour so related to the axis of rotation of the disc and to the position of the axis relative to the window that said window will be covered in progressively varying amounts from said one end thereof with each full revolution of the disc.

3. A motor tuning indicator comprising a shell having a wall provided with an elongated slotlike window, means mounted in the shell and adapted to be actuated from the ignition circuit of an engine when in operation to produce intermittent flashes of light behind and for the full length of the window, a rotatable member of greater area than the window disposed parallel and adjacent thereto, means mounting the memher on the shell in position for movement across the Window, means formed with the member to provide a shutter of a size and shape relative to the window so as to cover the same in progressively varying amounts from one end to the other with the rotation of the member in a certain direction and means to rotate the member in said direction and at a constant speed so that the shutter will recurringly thus cover the window.

'4. A motor tuning indicator comprising a shell having a wall provided with an elongated slotlikewindow, means mounted in the shell and adapted to be actuated from the ignition circuit of an engine when in operation to produce intermittent flashes of light behind and for the full length of the window, a rotatable disc of greater area than the window disposed parallel and adjacent thereto, means mounting the disc on the shell for rotation across the window and comprising an axial sup-port positioned beyond and arranged to register therewith with each full revolution of the disc.

' HARLOW A. REED. 

